Combustor Turbine Interface Studies—Part 2: Flow and Thermal Field Measurements

Abstract

Most turbine inlet flows resulting from the combustor exit are nonuniform in the near-platform region as a result of cooling methods used for the combustor liner. These cooling methods include injection through film-cooling holes and injection through a slot that connects the combustor and turbine. This paper presents thermal and flow field measurements in the turbine vane passage for a combustor exit flow representative of what occurs in a gas turbine engine. The experiments were performed in a large-scale wind tunnel facility that incorporates combustor and turbine vane models. The measured results for the thermal and flow fields indicate a secondary flow pattern in the vane passage that can be explained by the total pressure profile exiting the combustor. This secondary flow field is quite different than that presented for past studies with an approaching flat plate turbulent boundary layer along the upstream platform. A counter-rotating vortex that is positioned above the passage vortex was identified from the measurements. Highly turbulent and highly unsteady flow velocities occur at flow impingement locations along the stagnation line.

Experimental and Numerical Investigation of Combustor-Turbine Interaction Using an Isothermal, Nonreacting Tracer

“…"Inlet profile generators" are then used to approximate the combustor exit flow supplied to the turbine rig. State-of-the-art work along these lines include, most recently, the work of Colban and co-workers [3,4], Barringer and co-workers [5,6], Povey and Qureshi [7,8], and Simone et al [9]. These past approaches have led to an improved understanding of the sensitivity of the turbine to the various inflow parameters separately, e.g., OTDF level.…”

Heat transfer and film-cooling for the endwall of a first stage turbine vane

“…One of the key findings was that the endwall adiabatic effectiveness distributions showed extreme variations across the vane gap with much of the coolant being swept across the endwall toward the suction side corner. Granser and Schulenberg [18], Colban et al [15], and Zhang and Moon [19] all reported similar adiabatic effectiveness results in that higher values occurred near the suction side of the vane relative to the pressure side. Based on their measurements, Roy et al [20], however, indicated that the coolant migrated toward the pressure side of the vane.…”

“…For this latter case, the rotation of the passage vortex was predicted to be counter-clockwise since the total pressure was lower towards the midspan. The experimentally measured secondary flows by Colban et al [15] in Fig. 3b shows what one might expect for an actual turbine where the upstream boundary layer is film-cooled in the combustor section and there is a backward facing slot flow at the combustor-turbine interface.…”

“…The experiments for this study were performed in a low speed, closed-loop wind tunnel facility, shown in Fig. 5a that has previously been described by Barringer et al [31] and Colban et al [15]. The flow in the wind tunnel is driven by a 50 hp axial vane fan, which is controlled by a variable frequency inverter.…”

“…(a) Measured secondary flows in a turbine vane passage with a two-dimensional turbulent boundary layer[9] and (b) for a case simulating the upstream effects of a combustor liner with combustor-turbine leakage flow[15].…”